Removable brush-head for ultrasonic toothbrush

ABSTRACT

A removable brush-head for an ultrasonic toothbrush for daily dental hygiene purposes, including a plurality of bristle clusters, a substantially tubular body constructed of a flexible material and tensioning means securing the brush-head to the ultrasonic device, providing for the efficient transmission of ultrasonic frequency vibrations from the device via the brush-head to the teeth and gums of the user to loosen and remove soft plaque therefrom.

RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 07/674,123, now U.S. Pat. No. 5,138,733, filed Mar. 25, 1991entitled "Ultrasonic Toothbrush".

BACKGROUND

1. Field of Invention

This invention relates to toothbrushes. More particularly the inventionis concerned with an apparatus facilitating the use of ultrasonic energyto assist an otherwise manual toothbrush in loosening and removing softplaque from the teeth of the user on a substantially dialy basis. Aspecific concern of the invention is an apparatus that carries thebristle clusters, which is readily replaceable as wear of the bristlesoccur.

2. Description of Prior Art

Numerous attempts have been made to develop an apparatus to removeplaque or tartar from the surface of the teeth. Some of the devicesutilized sonic and/or ultrasonic energy. The devices utilizing sonic orultrasonic energy can be grouped into three distinct categories.

One approach is the utilization of only fluids as a medium of energytransmission and plaque removal by placing an ultrasonic transducer intothe middle of the mouth. This approach is impractical andphysiologically dangerous due to the high energy levels it requires tobe effective in absence of any mechanical scrub bing, and theuncontrolled, variable, user dependent distance between the transducerand the teeth. A typical example is U.S. Pat. No. 3,760,799.

The second approach is the application of ultrasonic energy to vibratethe toothbrush. While these teachings are aged, no application to datahas demonstrated the practical feasibility of carrying out the sciencein this manner. The significant drawback of some these proposals is thatthe toothbrush or applicator is solidly attached, otherwise fixed to thetransducer, making replacement of the brush difficult and expensive,taking the device out of the economically affordable daily dentalhygiene device category for the general population. Examples of thesedevices can be found in the following U.S. Patents: U.S. Pat. Nos.4,192,035 and 4,333,197 and 4,787,847.

The third and only theory reduced to practice to data is to removehardened or calcified plaque colonies from the surface of the teeth oninfrequent periodical basis. This art has been made available toprofessional dentists in the form of a high energy device that couplesthe ultrasonic energy to the teeth by a metal probe. While safe in thehands of the highly skilled and professionally trained dentists orhygienists, these devices are not suitable for daily use by the generalpopulation. Such devices could cause damage to the surface of the teethand the surrounding tissue when utilized by un-trained novice consumers.What has occurred to date is that notwithstanding the teachings of theprior art, the ability to utilize ultrasonic energy to assist theconsumer in the daily maintenance of oral hygiene in a safe andeffective manner has remained unsolved.

OBJECTS AND ADVANTAGES OF THE INVENTION

Responding to the above described unsolved needs, this inventionprovides an ultrasonic toothbrush that is safe and effective to assistthe consumer in the daily maintenance of oral hygiene. The inventionattains this goal by positioning a piezoelectric transducer in the headsection of an otherwise manual toothbrush. The piezoelectric crystal,resonating at or about its resonant frequency, emits ultrasonic wavesbetween the bristles and couples the energy to the surface of the teethvia the dentifrice in the users mouth.

An object of the present invention is to provide a safe ultrasonicenergy coupling mechanism to the user's teeth to dislodge and removesoft plaque.

An other object of the invention is to provide an effective cleaningdevice while reducing the ultrasonic energy level to the point where thedaily application in the hands of an un-trained novice will not harm thesurface of the teeth or the surrounding soft tissue.

A further object is to provide an inexpensive removable brush component,independent from the sealed ultrasonic energy emitter, that can beeasily replaced by the consumer. The brush component must provide foradequate interface between the surfaces of the main body containing thepiezoelectric transducer, and the surfaces of the brush component, forefficient transmission of the ultrasonic energy.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, in which certain modes of carrying out thepresent invention are shown for illustrative purposes:

FIG. 1 shows a longitudinal cross section of the invention in thereplaceable brush-head configuration, including a battery powereddriving circuitry.

FIG. 2 and FIG. 3 show the lock-in attachment methodology of thebrush-head to the handle of the ultrasonic device, in a cross sectionalview.

FIG.4 and FIG. 5 and FIG. 6 show the brush-head unlocking tool and theremoval methodology of the brush-head from the main body of the device.

FIGS. 6A-6E show an embodiment of the attachment and removalmethod-ology of the brush-head to and from the handle of the device.

FIG. 7 shows an alternative embodiment of the invention where thereplaceable brush element includes the piezoelectric crystal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring in detail to the drawings, the reference numerals herein referto the like numbered parts in the drawings. In the following discussion,unless otherwise qualified, the term "ultrasonic" refers to eithersubsonic, sonic, or ultrasonic frequencies.

An ultrasonic toothbrush 20, in accordance with the present invention,is shown in FIG. 1. The toothbrush comprises of a handle 22 constructedof a rigid material, a battery pack 24, an electronics driving module26, a piezoelectric transducer 28, connecting wiring 30, and a removablebrush-head 32 made of a flexible material that encompasses a pluralityof bristle clusters 34. The toothbrush is shown in a typical cleaningposition, the bristle clusters 34 in contact with the teeth 36 in theoral cavity 38. The low voltage DC energy supplied by the battery pack24 is converted to an ultrasonic frequency DC current by the electronicsdriving module 26, which is connected to the piezoelectric transducer 28by the connecting wiring 30. The piezoelectric crystal resonates,expands and contracts volumetrically, in tune with the frequencysupplied by the electronics driving module 26 and thereby converts theelectronic energy into sound-wave energy. The sound-waves driving thedentifrices in the mouth of the user against the teeth 36 causing mildcavitation within the dentifrices at the junction with the teeth,resulting in a loosening effect on the soft plaque on the surface of theteeth and in the periodontal pockets formed in the gums around the neckof the teeth. The loosened soft plaque is then dislodged by the bristleclusters 34 of the toothbrush 20 by the normal brushing movements of theuser.

The length of the bristle clusters 34 is selected to space thetransducer 28 within an effective and controlled optimum distance to theteeth, allowing the reduction of the sound energy to biologically safelevels for routine daily application without causing harm to the surfaceor root structure of the teeth, and the surrounding soft tissue.

FIG. 2 and FIG. 3 illustrates the lock-in attachment methodology of thebrush-head 32 to the handle 22. To achieve a firm attachment, thebrush-head 32 incorporates a tapered tongue section 40 and the handleincorporates a matching groove 42. To install a replacement brush-head32, the user engages the rigid nose 44 section of the handle 22 with theflexible mouth 46 section of the brush-head 32. Upon engagement, theuser forces the brush-head 32 upon the handle 22 until the movement isstopped by the lower mating surfaces 48 and 50 of the brush-head 32 andhandle 22 respectively, and the tongue 40 snaps into the groove 42.

FIGS. 4, 5, and 6 illustrate the un-locking methodology of an otherconfiguration brush-head 32 from the handle 22. The brush-head 32incorporates a tapered abutment 52 on each side that increases in sizetoward its mouth 46. The internal cavity of the mouth 46 is tapered 54,and increasing in size toward the abutments 52, forming a gap betweenthe brush-head 32 and the handle 22 adjacent to the abutments 52. Aremoval tool 56 constructed of a material with superior strength andrigidity to the flexible brush-head 32 material, comprises a cavity thatmatches the lower and straight side dimensions of the brush-head 32 butlarger than the brush-head 32 in the vertical dimension. As the userslides the rigid removal tool 56 upon the flexible brush-head 32, thesides with the abutments 52 of the brush-head 32 deform inwardly,causing the top section of the brush head 32 with the tongue 40 to flexinto the gap 47, out of the groove 42 of the handle 22, therebyun-locking the brush-head 32 from the handle 22.

FIGS. 6A-6E show an embodiment of the attachment and removal methodologyof the brush-head to and from the handle of the device.

FIG. 6A shows the preferred brush-head 72 constructed of a flexiblematerial with varying wall thicknesses, incorporating a cavity 73 havinga flat bottom surface 74 adjacent to the bristle clusters 34 and atapered upper surface 78 opposite to the bristle clusters 34. The wallopposite to the bristle clusters 34 incorporates a slot 76 for thepurpose of locking the brush-head 72 into place on the handle 22 and tosecure it against accidental removal. The handle 22 constructed of arigid material, incorporates a flat bottom surface 84 and a taperedupper surface 80, wherein the angle 81 of the tapered upper surface 80is larger than the angle 79 of the tapered upper inside surface 78 ofthe brush-head 72 cavity 73. The handle 22 also comprises a groove 42adapted to receive the flexible end portion 82 of the brush-head 72. Thedimension 86 of the handle 22 is approximately the same as the dimension88 of the brush-head 72, while the dimension 90 of the handle 22 issignificantly larger than the dimension 88 of the brush-head 72.

FIG. 6B shows the installation process of the brush-head 72 onto thehandle 22. The user aligns the flat inside surface 74 of the brush-head72 with the flat outer surface 84 of the handle 22, then proceeds topush the brush-head 72 onto the handle 22.

During the installation process, as shown in FIG. 6C and 6C', the largerangle 81 of the handle 22 expands the walls 94 and 96 of the brush-head72 which is constructed with a smaller angle 79. The vertical wallthickness 92 of the brush-head 72 is designed to be substantiallythinner than the bottom section 98 to assure that the expansion and theaccompanying deformation of the brush-head 72 takes place within theside walls 94 and 96. The thickness of the bottom section 98 iscalculated to assure that the inside flat surface 74 adjacent to thebristle clusters 34 of the brush-head 72 remains flat and not deformedby the expansion forces, and remains in intimate contact with thesurface 84 of the handle 22.

FIG. 6D describes the ultrasonic energy transmission methodology fromthe piezoelectric transducer 28 through the brush-head 72. When thebrush-head 72 is pushed fully onto the handle 22, and the side walls 94and 96 are expanded, the entire inside surface 74 of the brush-head 72is forced into a tight and intimate contact with the outside surface 84of the handle 22 by the tensional forces generated in the side walls 94and 96 of the brush-head 72. This feature of matching surfaces inintimate contact is important for the efficient transmission of theultrasonic energy from the piezoelectric crystal 28 through the handle22 to the brush-head 72 and the bristle clusters 34. The volumetricexpansion and contraction of the piezoelectric transducer 28 indicatedby the double headed arrows generates the sound waves indicated by thecurved lines, that are transmitted to the handle 22 and in turn to thebrush-head 72 external surfaces and to the bristle clusters 34. Thethickness 92 of the side walls 94 and 96 are also calculated to assurethat the stress generated by the expansion force does not exceeds theyield strength of the side walls 94 and 96. When designed in thismanner, the stress generated in the side walls 94 and 96 will provide aforce to maintain intimate contact between the surface 74 of thebrush-head 72 and the surface 84 of the handle 22 throughout the lifecycle of the brush-head 72.

FIG. 6E shows the locking methodology of the brush-head 72 to the handle22. As the end portion 82 of the brush-head 72 next to the slot 76passes over the thickest dimension 90 of the handle 22, it is positioneddirectly above the groove 42 of the handle 22. The tensional forces inthe side walls 94 and 96 pull the flexible end portion 82 of thebrush-head 72 into the groove 42 of the handle 22, thereby locking thebrush-head 72 into position on the handle 22. The angularity of surface100 is designed to prevent movement of the brush-head 72 by the forcesgenerated of the bristle clusters 34 as they are rubbed against theteeth of the user, but to allow the removal of the brush-head 72 fromthe handle 22 when a significant axial pulling force is applied by theuser.

FIG. 6E further shows the removal methodology of the brush-head 72 fromthe handle 22. The user presses a wedge 104 into a gap 102 formedbetween the brush-head 72 and the handle 22, perpendicular to thelongitudinal axis of the handle 22. As the wedge penetrates, it widensthe gap 102 and forces the brush-head 72 away from the handle in anaxial motion, while the flexible end portion 82 of the brush-head 72rides up on the angle 100 of the handle 22, releasing the brush-head 72.In practice, numerous other tools could replace the wedge 104 in theaction of widening the gap. A screwdriver or a coin being twisted in thegap could fulfill the same function.

FIG. 7 shows an alternative embodiment of the invention, where theultrasonic toothbrush 70 comprises of an AC line connector 66, a handle64, an electronics module 26, a low voltage high frequency DC connector58, and a replaceable brush element 62 that is further comprised of aplurality of bristle clusters 34, a piezoelectric transducer 28,connecting wiring 30, and an other connector 60. The electronics moduleis energized by conventional AC house current through the line connector66. The AC house current is converted to a low voltage, ultrasonicfrequency DC current by the electronics module 26, which is connected tothe piezoelectric transducer 28 by the connecting wiring 30 through theconnectors 58 and 60. The piezoelectric crystal resonates, expands andcontracts volumetrically, in tune with the frequency supplied by theelectronics driving module 26 and thereby converts the electronic energyinto sound-wave energy. The sound-waves driving the dentifrices in themouth of the user against the teeth 36 causing mild cavitation withinthe dentifrices at the junction with the teeth, resulting in a looseningeffect on the soft plaque on the surface of the teeth and in theperiodontal pockets formed in the gums around the neck of the teeth. Theloosened soft plaque is then dislodged by the bristle clusters 34 of thetoothbrush 70 by the normal brushing movements of the user.

CONCLUSION, RAMIFICATIONS AND SCOPE OF THE INVENTION

It can be seen that the invention provides a safe and effectiveultrasonic toothbrush that can be utilized by any novice in the dailymaintenance of oral hygiene. The fluid coupled ultrasonic energy, wheremetallic contact with the teeth has been eliminated, and the relativelylow level but effective energy provides outstanding safety for both theteeth and the surrounding soft tissue. The reduced energy requirement ismade possible by the controlled distance between the piezoelectrictransducer and the teeth, that is established by the length of thebristle clusters. In particular, the removable toothbrush head allowsfor frequent replacement of the bristle clusters as appropriate.

While the preceding description contain many specificities, these shouldnot be construed as limitations on the scope of the invention, butrather as an exemplification of a preferred and additional embodimentsthereof. Many other variations are possible. Skilled artisans willreadily be able to change dimensions, shapes and construction materialsof the various components described in the embodiments and adopt theinvention to all types of sonic energy applications, from the subsonicrange through sonic and to the ultrasonic range. Accordingly, the scopeof the invention should be determined not by the embodimentsillustrated, but by the appended claims and their legal equivalents.

I claim:
 1. A brush device for use in personal dental hygiene care as areplaceable member of a dental hygiene device comprising:a plurality ofbristle clusters for carrying dentifrice; a substantially tubular bodyconstructed with flexible walls with means securing said bristleclusters within one of the said flexible walls forming a tight fit tothe said dental hygiene device, at least one abutment extending from atleast one of the walls toward the center forming a tight fit into areceptacle formed in the said dental hygiene device while the otherwalls are forming a fit with substantial clearance over said dentalhygiene device.
 2. The brush device of claim 1 including means ofdeflecting said flexible walls with said substantial clearance over saiddental hygiene device inward causing the other one or more said flexiblewalls comprising said tight fitting abutment to move outward unlockingsaid brush device from said dental hygiene device.
 3. A brush device foruse in personal dental hygiene care as a replaceable member of anultrasonic dental hygiene device having a mating part thereforcomprising:a plurality of bristle clusters for carrying dentifrice; asubstantially tubular body having an open end for receiving the dentalhygiene device, and including top and bottom walls diverging from eachother in the direction of the open end, and side walls interconnectingthe top and bottom walls defining a tapered cavity smaller than themating part of said dental hygiene device, said tubular body to beforced to fit onto the larger mating part of the said dental hygienedevice, said walls being flexible with means securing said bristleclusters within one of said top and bottom walls and having at least oneinner surface portion in the cavity opposite the bristle clusters forforcibly engaging a corresponding surface of the mating part when fitthereon, other said flexible walls including tensioning means toforcibly pull said flexible wall containing said bristle clusters intointimate contact against said dental hygiene device to conductvibrations to ultrasonic frequency from said dental hygiene device tothe surface within said tubular body and to said bristle clusters, thesaid tubular body and said bristle clusters to be received within thehuman mouth for conducting said vibrations to the said dentifrice toloosen soft plaque on the surface of the teeth and the gums and movedacross tooth and gingival surfaces for dislodging the loosened softplaque therefrom.
 4. The brush device of claim 3 wherein at least one ofthe said flexible walls includes means operated by the tensioning ofsaid flexible walls to retain said brush device on the said dentalhygiene device against the forces generated by the friction between saidbristle clusters and the teeth of the user, the said brush device beingremovable by an application of an axial force.
 5. The brush device ofclaim 3 wherein at least the flexible wall opposite to the said flexiblewall containing said bristle clusters includes a slot to allow thetensions generated by the expanding side walls to pull the flexible endportion of said flexible wall into a grove in the handle of said dentalhygiene device to retain said brush device on the said dental hygienedevice against the forces generated by the friction between said bristleclusters and the teeth of the user, the said brush device beingremovable by an application of an axial force.
 6. The brush device ofclaim 3 wherein one of the said flexible walls is constructed to form agap between the said brush device and the said dental hygiene device,the said gap being substantially perpendicular to the longitudinal axisof the said brush device to receive means to disengage said brush devicefrom said dental hygiene device.
 7. The brush device of claim 3 whereinthe dental hygiene device is a subsonic device.
 8. The brush device ofclaim 3 wherein the dental hygiene device operates in the audible soundfrequency range.
 9. The brush device of claim 3, wherein the at leastone inner surface portion in the cavity comprises a planar surfaceslated relative to a longitudinal axis of the mating part, said cavityhaving a relatively narrow inner portion and a relatively wide open end.10. The brush device of claim 9, wherein the slated surface acts as aninclined plane opposite a corresponding surface on the mating part. 11.A brush device for use in personal dental hygiene care as a replaceablemember of an ultrasonic dental hygiene device having a mating part and avibratory working surface comprising:a plurality of bristle clusters forcarrying dentifrice; having an open end for receiving the dental hyginedevice, and including top and bottom walls diverging from each other inthe direction of the open end, and side walls interconnecting the topand bottom walls a substantially tubular body defining a tapered cavityadapted to be smaller than a mating part of the said dental hygienedevice, to be forced to fit onto said larger mating part of the saiddental hygiene device, said walls being flexible including meanssecuring said bristle clusters within one of said top and bottom wallsand an inner wall portion within the cavity opposite the bristleclusters for engaging the vibratory working surface of the mating part,said flexible walls exerting tensioning force on said larger mating partto secure the inner wall portion of said flexible wall containing saidbristle clusters against vibratory working surface of the mating part ofsaid dental hygiene device to conduct vibrations of ultrasonic frequencyfrom said dental hygiene device to the said tubular body and saidbristle clusters, the said tubular body and said bristle clusters to bereceived within the human mouth for conducting said vibrations to thesaid dentifrice to loosen soft plaque on the surface of the teeth andthe gums and moved across tooth and gingival surfaces for dislodging theloosened soft plaque therefrom.
 12. A brush device for use in personaldental hygiene care as a replaceable member of an ultrasonic dentalhygiene device comprising:a plurality of bristle clusters for carryingdentifrice; a substantially tubular body containing a tapered cavityadapted to be smaller than the mating part of said dental hygienedevice, to be forced onto the larger mating part of the said dentalhygiene device, constructed with flexible walls with means securing saidbristle clusters within one of said flexible walls, other said flexiblewalls containing tensioning means to pull and hold said flexible wallcontaining said bristle clusters against said dental hygiene device toconduct vibrations to ultrasonic frequency from said dental hygienedevice to the said tubular body and said bristle clusters, the saidtubular body and said bristle clusters to be received within the humanmouth for conducting said vibrations to the said dentifrice to loosensoft plaque on the surface of the teeth and the gums and moved acrosstooth and gingival surfaces for dislodging the loosened soft plaquetherefrom, a flexible wall opposite said wall containing said bristleclusters includes a slot to allow the tensions generated by theexpanding side walls to pull the flexible end portion of said flexiblewall into a groove in the handle of said dental hygiene device to retainsaid brush device on the said dental hygiene device against the forcesgenerated by the friction between said bristle clusters and the teeth ofthe user, the said brush device being removable by an application of anaxial force.